Method for reliable high-performance recording of process data with numerically controlled industrial processing machines

ABSTRACT

Process data are recorded by accumulating process data in a delay-time critical cyclic time plane—e.g., a main processor clock—and storing the accumulated data in an data buffer memory having a FIFO characteristic using a cyclic clock. The data buffer memory is read out in a delay-time uncritical acyclic time plane—e.g., a pre-process clock—and the read out data are processed and stored as data sets in a log memory. To achieve synchronous recording of process data of different time planes, such as process data generated in a cyclic interpolator time plane and a cyclic position control time plane, the process data for position control are accumulated over the time interval of an interpolation clock cycle and provided synchronously with the data of the interpolator for recording.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the priority of German Patent ApplicationSerial No. 101 44 788.4, filed Sep. 11, 2001, pursuant to 35 U.S.C.119(a)-(d), the subject matter of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a method for reliable,high-performance recording of process data with numerically controlledindustrial processing machines, such as machine tools and robots, aswell as a corresponding device, in particular a numeric controller.

[0003] Heretofore, there is a lack of methods to allow collection ofdata of different time planes on a CNC without data loss and to provideexternal components for further processing in near real time. Instead,conventional methods implement for each intended application a separatedata recording which is specifically tailored to the application'srequirements, as listed in the following examples.

[0004] For graphic simulation, a number of data are recorded which arecollected at the time when the software for the CNC is developed. Onlydata of the so-called interpolator time plane are taken intoconsideration. Details of a numeric control for machine tools using aninterpolator are given, for example, in EP 0 513 417 B1 wherein pointslocated between defined path points of a trajectory are clocked at aninterpolation cycle which is longer than a position controller cycle anddefines the interpolator time plane. The patent reference EP 0 513 417B1 is incorporated herein by reference in its entirety.

[0005] In a so-called oscilloscope function, only data for a servocontrol are initially recorded. The storage capacity of the CNC istypically limited to only this function, which severely restricts themaximum possible recording duration. Graphic processing is then doneoff-line subsequent to the recording.

[0006] Moreover, external components (for example, an operator interfaceand/or a man-machine-interface MMI) cyclically read the process data,which makes it almost impossible to recognize rapid changes. Such methodis only suitable for display on a display screen (e.g., current values),but not for additional processing.

[0007] These individual solutions result in significant development andmaintenance expenses. Typically, a suitable recording method has to bedeveloped for each new application. This may be possible only in alimited fashion if the application is implemented by an OEM (third-partymanufacturer) or by an external software house as an add-on.

[0008] It would therefore be desirable and advantageous to enable auniform recording of process data of numerically controlled industrialprocessing machines (CNC), which can be used for a graphicallysimulating the process flow of the machine synchronous with themachining operation; providing an oscilloscope function (graphicrepresentation of temporal correlation between several process data) foreasy startup of the machine; monitoring the process data to enhance thesafety of personnel, machine and workpiece (e.g., monitoring breakage ofthe workpiece for rapidly lifting the tool from the workpiece);transmitting process data via a network (e.g. Internet) for remotediagnosis by the manufacturer of the machine or the controller; andfacilitating addition of OEM applications to solve technical problems,e.g., by a manufacturer of the machine.

[0009] It would further be desirable and advantageous to enablerecording of process data during operation of numerically controlledindustrial processing machines, which can satisfy the aforedescribedrequirements and obviates the disadvantages of conventional individualsolutions.

SUMMARY OF THE INVENTION

[0010] According to one aspect of the invention, a method for reliablehigh-performance recording of process data with numerically controlledindustrial processing machines, such as machine tools or robots,includes collecting process data in a delay-time critical cyclical timeplane and storing the process data in cyclical intervals in an databuffer memory having a first-in-first-out characteristic (FIFO;OEM-FIFO), adding the buffer memory in a delay-time non-critical acyclictime plane, and processing and storing the read out data are as datasets in a log memory (FIFO-FILE).

[0011] Embodiments of the invention can have one or more of thefollowing features. The log memory can have a First-In-First-Outcharacteristic, and the data buffer memory (FIFO) and the log memory(FIFO-FILE) can be formed as a ring buffer. For synchronous recording ofprocess data in different time planes, the process data can be generatedin a cyclic interpolator time plane (IPO) and a cyclic position controltime plane (SERVO), and process data associated with the positioncontrol can be collected over a time of an interpolation clock cycle andprovided for recording synchronously with the collected process data.

[0012] Deleting the data sets read from the log memory ensures thatthere is always sufficient storage capacity for new entries.Advantageously, a list with data is provided that parametrizes whichincoming process events to be recorded. Additional advantageousfunctionality can be achieved by providing data read from the databuffer memory with header information when they are processed into datasets. Packets lost due to missing numbers can be identified from theheader information since consecutive data sets are numberedsequentially. Advantageously, by using the header information, a dataset can be associated with an event that initiated the recording.

[0013] Advantageously, at the start of a recording, a parameter can beset that defines a specified process event and a corresponding thresholdvalue, and the recording can be automatically terminated when thethreshold value is exceeded and/or underrun. Alternatively, when thethreshold value is exceeded and/or underrun, the recording can beterminated with a delay that corresponds to a predeterminable number ofprocess events. This guarantees, for example in the event of a toolbreakage, that the critical operating status is recorded. In addition, arecording of process data can be initiated and/or terminated by a partsprogram using a suitable programming command.

[0014] According to another aspect of the invention, a device—inparticular in form of a programmable numeric controller—is provided thatis capable of carrying out the aforedescribed method steps of theinvention.

[0015] According to yet another aspect of the invention, a computerprogram product running on a digital computer is provided, wherein theprogram product can be loaded directly into the internal memory of thedigital computer and comprises software sections for carrying out theaforedescribed method steps of the invention.

[0016] According to still another aspect of the invention, a numericcontroller for reliable high-performance recording of process data,includes a data buffer memory having a first-in-first-out characteristic(FIFO; OEM-FIFO) for storing process data collected in a delay-timecritical cyclical time plane of the numeric controller; and a master logmemory (FIFO-FILE) for storing data read out from the buffer memory in adelay-time non-critical acyclic time plane and processed as data sets.

[0017] The proposed solution implements a recording method which canachieve at least one of the following advantages:

[0018] general, open access data interface also for parameterization,

[0019] flexible initiation of data recording,

[0020] unrestricted selection of the data to be recorded (date,initiating event, format),

[0021] identification marks for lost data sets,

[0022] trigger possibility for controlling the recording duration,

[0023] synchronization of servo data with interpolator and/or IPO data(servo→IPO interface),

[0024] decoupling of the recording in the IPO from the data output,

[0025] log file with FIFO characteristic (dataadministration→communication interface), and

[0026] continuous transmission chain from servo to MMI.

[0027] The aforedescribed logging functionality according to theinvention enables a high-performance synchronous recording of data inthe time plane of an interpolator (interpolation timing signal). In thisway, different functions can be implemented on a numeric controller, forexample a graphic simulation of the machining synchronous with themachining operation itself, monitoring tool breakage or a diagnosis ofsynchronous events.

[0028] The recording is hereby done in relation to specified processevents and the system (e.g., IPO timing, set change, start/stop of axialmovement, tool change, etc.). A list of data to be recorded can bepredefined for each event. Preferably, all values/parameters that aredefined in an operator console interface BTSS are available.

[0029] The recorded data are preferably stored in a file in a passivefile system of the controller (in the form of a so-called log file PF).These data can be uploaded simultaneously for logging to a passive filesystem of the controller, so that the limited memory of the controllerkernel (NCK) does not limit the amount of logged data.

[0030] The logging function is preferably parameterized via the operatorconsole interface BTSS. The logging function can be adapted formulti-user operation, i.e., through parallel access for differentapplications.

BRIEF DESCRIPTION OF THE DRAWING

[0031] Other features and advantages of the present invention will bemore readily apparent upon reading the following description ofcurrently preferred exemplified embodiments of the invention withreference to the accompanying drawing, in which:

[0032]FIG. 1 shows a schematic block diagram of an internalconfiguration of a log file according to the invention; and

[0033]FIG. 2 shows a schematic diagram of a FIFO buffer memory as a ringbuffer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] Certain useful background information will now be provided beforediscussing the actual technical implementation.

[0035] The entire parameterization of data recording (specifying theformat and the events for recording the data) is implemented via ageneral open-access data interface BTSS. Access to the BTSS is enabledfor parts programs, NCK-OEM compile cycles and, with the help of avariable service, also for external components (MMI). This openaccessibility allows the manufacturer of the controller, themanufacturer of the machine, the OEM developer and also the end-user tomake use of the recorded data.

[0036] Various system events can initiate data recording (for example,NC start/stop, beginning/end of a set, tool change, start/stop of axialmovement, IPO timing pulse). In addition to the system events, arbitraryOEM events can also be defined by NCK-OEM compile cycles. In addition,data recordings can also be initiated by parts programs.

[0037] Data to be recorded (date, initiating event, format) can beflexibly selected. Each of these events can be set to indicate if dataare to be recorded or not. A list of arbitrary process data can beassembled for those events that are to be recorded. In addition, theform of the recording (e.g., format, environment) can also be selected.

[0038] Each recorded data set includes a header aiding in theidentification of lost data sets. In addition, the header can alsoassociate the data set with the event that initiated the recording.

[0039] At the start of the recording, a BTSS variable can be selectedwhose values will subsequently be monitored. If the value underruns orexceeds a certain threshold value, then a trigger is activated and therecording is automatically stopped. This allows logging of criticaloperating states.

[0040] The servo process data are accumulated during an IPO timing pulseand made accessible to the BTSS. In this way, the process data of theIPO and the process data of the servo are synchronized for recording thedata in the IPO.

[0041] Recording in the IPO is decoupled from the data storage. The dataare recorded in the time plane of the IPO initially in a data formatwhich is optimized for delay-time. The data are stored in a data regionhaving First-In-First-Out (FIFO) characteristic. The FIFO is read out inthe delay-time uncritical acyclic time plane, the data are processed(e.g., format conversion) and stored in a so-called log file PF in thefile system (e.g., SRAM)

[0042] The log file has typical file characteristics, i.e., it can be,for example, copied, deleted, edited or read by a domain upload process.In addition, the log file operates during the domain upload like a FIFO,wherein read data sets are deleted from the log file, thereby creatingspace for new entries. The data can also be communicated to externalcomponents in near real time. The existing memory configuration of theCNC does not limit data recording as a result of external safeguardingand/or additional processing of the data.

[0043] Process data can be recorded and read out synchronously in nearreal time with the aforedescribed three intermediate data memories whichfunction as buffers between the individual time planes of the CNCsoftware. Buffers with sufficient capacity ensure that no data are lost.Each time plane only performs those tasks that are absolutely necessaryin that specific time plane and delegates the other tasks to the nextlower time plane. In this way, the manufacturing process is typicallynot significantly affected by the data recording process.

[0044] The diagram of FIG. 1 shows the internal configuration of a logfile PF according to the invention. The data to be logged are enteredinto a so-called log file. In the present embodiments, this is aspecific file type of the passive file system. As a new file type, thelog file includes as an essential characteristic a fast FIFO buffermemory FIFO. This buffer memory FIFO is operated from the main processHL (switch S1 controls synchronously with the clock of HL). Data D whichare provided by a protocol manager PM in response to defined events Eare imported in the buffer memory FIFO synchronously with the mainprocess HL.

[0045] The data of the buffer memory FIFO are then imported (uploaded)from the buffer memory into the actual log memory FIFO-FILE in the timeplane of the pre-process VL (switch S2). Only the FIFO-FILE is visibleto and accessible from the outside as the actual log file PF (forexample, for reading and processing the accumulated log data).

[0046] As discussed below, an OEM-FIFO having the same functionality canbe connected in parallel to the buffer memory FIFO to enable possibleupgrades by OEM manufacturers which can then take advantage of thefeatures of the log file.

[0047]FIG. 2 shows a configuration of the two FIFO intermediate memoriesFIFO and OEM-FIFO implemented as a ring buffer with exemplary data setsDs1, Ds2, . . . , Ds.x. In this way, data that have been read out canessentially be deleted and/or their memory locations can be madeavailable by setting a pointer to the next free memory location withinthe ring buffer.

[0048] The NCK-compile cycle can block and release a transmission ofdata form a FIFO buffer memory to the FIFO file.

[0049] The comparatively fast FIFO buffer memory FIFO accepts the loggeddata with the IPO clock until the data can be transferred in the timeplane of the pre-process to the log file. If several process events areactive and/or parameters are to be set for several data values, then thebuffer memory can overflow (for example, overflow of the ring bufferwhen more data are entered into the main process than can be read out bythe pre-process), causing data loss. The capacity of the buffer memoryFIFO is selected to be sufficiently large for the existing applications.For OEM applications, however, where large quantities of data have to berecorded (e.g., for tool overload monitoring), the standard size of thebuffer memory may not be sufficient.

[0050] It may also be possible to save the actual log files FIFO-FILEduring the logging process in the time plane of the pre-process VL. Inthis way, operating states of interest (for example, overloadconditions) can be retained for graphic processing. This safety feature,unlike the original file, operates like a “normal” file (no FIFOcharacteristic and no upload characteristic with deletion). The loggingoperation continues in parallel without interruption.

[0051] Data of events to be logged can belong to the time plane of theinterpolator IPO, whereas other data can belong to the time plane of thepre-process. It should be noted that a user is permitted tosimultaneously activate only events belonging to the same time plane. Alist of data to be logged can be defined for each event.

[0052] In certain applications, the logging process has to record dataover long time periods, while these data may be relevant only for ashort time (for example, to monitor tool breakage). In this case, theoperator initially does not read the data from the log file PF, so thatthe data are recorded in the log memory FIFO-FILE according to the FIFOprotocol. When the file is full, the oldest recordings are purged andreplaced with the newer recordings.

[0053] However, it should be possible to timely stop data logging, sothat the relevant data are retained in the log file PF. For thispurpose, the following enhanced functionality is provided.

[0054] Each user can determine a process event whose value is monitoredduring each logging operation. This value is compared as before with athreshold value. A positive result of the comparison indicates that thelogging process should be stopped automatically. However, the processneed not be stopped immediately, but can be stopped after a delay of apredetermined number of events (delay).

[0055] Assuming that the events are distributed predictably anduniformly over time (which is typically the case for events occurringsynchronously with the interpolation clock), then a number of events canbe set equal to a time duration. The specified capacity of the logmemory FIFO-FILE accepts a certain number of events and can therefore beviewed as a time window. The delay moves this time window.

[0056] If the delay is very long in relation to the log file, then thetrigger may fall outside the time window. A simple example is describedbelow to illustrate the logic behind this:

[0057] The x-value and y-value are to be recorded synchronously with theinterpolation clock. The log file has capacity of, for example, 6 datasets and/or interpolation clock cycles. The trigger signal should besent when the y-value exceeds a value of 50. 3 additional data setsshould be recorded after the trigger signal.

[0058] Logging of server data will now be described in detail. Thelogging of servo data has certain particularities from the system'sperspective, since the data exist in a time plane (servo) different fromthe time plane in which they were recorded (interpolation or IPO).

[0059] From the perspective of the user, the servo data are typicallypart of the operator console interface BTSS and are therefore treatedthe same as all other data to be logged.

[0060] While the invention has been illustrated and described inconnection with currently preferred embodiments shown and described indetail, it is not intended to be limited to the details shown sincevarious modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention. Theembodiments were chosen and described in order to best explain theprinciples of the invention and practical application to thereby enablea person skilled in the art to best utilize the invention and variousembodiments with various modifications as are suited to the particularuse contemplated.

[0061] What is claimed as new and desired to be protected by LettersPatent is set forth in the appended claims and their equivalents:

What is claimed is:
 1. A method for reliable high-performance recordingof process data with numerically controlled industrial processingmachines, such as machine tools or robots, comprising the steps of:collecting process data in a delay-time critical cyclical time plane;storing the process data in cyclical intervals in a data buffer memoryhaving a first-in-first-out characteristic (FIFO; OEM-FIFO), reading thedata buffer memory in a delay-time non-critical acyclic time plane, andprocessing and storing the read out data as data sets in a log memory(FIFO-FILE).
 2. The method of claim 1, wherein the log memory also has aFirst-In-First-Out (FIFO) characteristic.
 3. The method of claim 1,wherein the data buffer memory (FIFO) and the log memory (FIFO-FILE) areformed as a ring buffer.
 4. The method of claim 1, wherein the processdata are generated in a cyclic interpolator time plane (IPO) and acyclic position control time plane (SERVO) and the process dataassociated with the position control are collected over a time of aninterpolation clock cycle and provided for recording synchronously withthe collected process data.
 5. The method of claim 1, wherein the datasets are always deleted in the data buffer memory after having been readfrom the data buffer memory.
 6. The method of claim 1, and furthercomprising the step of providing a list with data that define parametersof those process events that are to be stored in the log memory.
 7. Themethod of claim 1, and further comprising the step of providing the dataread from the data buffer memory with a header information before beingprocessed into data sets.
 8. The method of claim 7, wherein the headerinformation includes sequential numbering of consecutive data sets. 9.The method of claim 7, wherein the header information associates a dataset with an event that initiated storing of the process data in the logmemory.
 10. The method of claim 1, and further comprising the steps ofsetting a parameter that defines a specified process event and acorresponding threshold value before recording the process data,comparing the process data with the threshold value, and automaticallyterminating recording the process data when the process data exceed orunderrun the threshold value.
 11. The method of claim 10, wherein therecording is terminated with a delay corresponding to a predeterminablenumber of process events when the process data exceed or underrun thethreshold value.
 12. The method of claim 1, and further comprising thestep having a parts program provide a programming command to one ofinitiate and terminate recording of the process data.
 13. A device forreliable high-performance recording of process data with numericallycontrolled industrial processing machines, such as machine tools orrobots, comprising: a protocol manager collecting process data in adelay-time critical cyclical time plane; a data buffer memory having afirst-in-first-out characteristic (FIFO; OEM-FIFO) for storing theprocess data in cyclical intervals, and a log memory (FIFO-FILE) thatreads the data buffer memory in a delay-time non-critical acyclic timeplane, and processes and stores the read out data as data sets.
 14. Thedevice of claim 13, implemented as a programmable numeric controller.15. A computer program product executed on a digital computer, thecomputer program product including computer instructions for causing thedigital computer to collect process data in a delay-time criticalcyclical time plane; store the process data in cyclical intervals in adata buffer memory having a first-in-first-out characteristic (FIFO;OEM-FIFO), read the data buffer memory in a delay-time non-criticalacyclic time plane, and process and store the read out data as data setsin a log memory (FIFO-FILE).
 16. A numeric controller for reliablehigh-performance recording of process data, comprising. a data buffermemory having a first-in-first-out characteristic (FIFO; OEM-FIFO) forstoring process data collected in a delay-time critical cyclical timeplane of the numeric controller; and a log memory (FIFO-FILE) forstoring data read out from the buffer memory in a delay-timenon-critical acyclic time plane and processed as data sets.
 17. Thenumeric controller of claim 16, wherein the log memory has aFirst-In-First-Out (FIFO) characteristic.
 18. The numeric controller ofclaim 16, wherein the data buffer memory (FIFO) and the log memory(FIFO-FILE) are formed as a ring buffer.